1. Field of the Invention
The present invention relates to engine emission sampling for emissions characterization, emissions control technology verification, vehicle maintenance and other purposes. In particular, the invention pertains to a self-contained transportable unit for sampling exhaust emissions from vehicles and other sources both mobile and stationary.
2. Description of the Prior Art
Current environmental requirements often require investigators to conduct representative exhaust emissions data from motor vehicles and other emissions-generating sources such as remote power generating plants and the like. Often, such testing is done at locations which are remote from a testing lab. This requires a readily portable sampling and analysis system. This equipment must effectively provide the same results as laboratory equipment consisting of a metered proportional volume sampling system and analysis system. The vehicle chassis dynamometer system found in a conventional emissions lab, is replaced by simply operating the vehicle under operational loads. The vehicle emissions then have to be measured to determine mass emission rates as per the laboratory system.
It is desirable to provide a portable system that has the capability to conduct the field testing as noted above. Therefore there is a need for a portable sampling system for the continuous measurement of exhaust emissions in a self-contained unit which may be attached to a vehicle for on-road testing or to any other emissions source.
Within the prior art, there are disclosed various systems for field sampling of exhaust emissions. For example, U.S. Pat. No. 4,586,367 by Louis et al., discloses an apparatus for measuring the particulate and/or gaseous content of exhaust emissions. The apparatus connects to a vehicle tailpipe and directs a portion of the affluent into a dilution chamber, downstream of which emissions contents are measured. U.S. Pat. No. 5,090,258 to Yamaski et al., discloses an analyzer which samples a portion of engine exhaust emission.
U.S. Pat. No. 5,410,907 to Ström et al., discloses an engine exhaust pipe sampler for measuring engine exhaust gases. The gases are directed into a dilution tunnel which directs a portion of the diluted exhaust gas into various analyzers. A central processor measures fuel flow and carries out various analyses.
U.S. Pat. No. 6,085,582 by Tripathi, et al. discloses an apparatus for measuring vehicle exhaust mass emissions comprising an exhaust inlet for collecting vehicle exhaust, a dilution air inlet connected with exhaust inlet to provide a diluted vehicle exhaust. A first analyzer which measures concentration of undiluted exhaust, a second analyzer which measures concentration of diluted exhaust, a meter which measures flow rate of dilute exhaust and a computer.
A particular requirement in this field is to provide for accurate measurement of emissions notwithstanding great variations in exhaust outflow. For example, a typical vehicle may vary greatly in its emissions between its idle phase, cruising, and acceleration or other heavy load modes of operation. Similarly, point emission sources such as generators can similarly vary in their emissions outflow. It is thus desirable to provide for a highly accurate means for measurement exhaust emissions, whilst still providing a readily transportable unit.
Potential applications for an emissions sampling apparatus and method of the general type characterized by this invention, includes a wide variety of exhaust emissions from both mobile sources and stationary sources. Mobile sources includes on and off road and non-road mobile sources, such as rail locomotives, boats, airplanes and equipment for use in construction, industrial, agricultural, mining and marine applications. Stationary sources includes electricity generators, power turbines and industrial equipment. Further, emissions may be sampled from a variety of gas, diesel or alternative-fuelled internal combustion engines as well as fuel cell technologies and micro turbines. The above listing is intended only to be representative of various applications, and not limiting of the invention in any respect.